Pete Whitstone Posted April 8, 2022 Share Posted April 8, 2022 Hi all, I have been eyeballing options for rear discs. One option is the SSBC A118 kit, which is supposed to be a bolt-on for the late big-bearing (Torino) 9 inch flanges, I'm pretty sure that's what an 81 would have. I don't have access to the detailed instructions, they don't give you that til you pony up the money. But I would assume that switching to rear discs would make deleting the residual pressure valve necessary. So where is that thing on the 81 braking system? I found some threads about the later plastic masters, and it hangs off the side of those. But the early masters don't seem to have that. Is the residual pressure valve part of the "multi-function" valve on the lines under the master? Or is it somewhere else? On that subject, I read that part of the function of the multi-function was to send some pressure to the rear to make sure the shoes engage, before it starts to send it to the front. Is that a necessary function of a disc/drum system and should not be used in a disc/disc system? Or is that just a function of vehicle dynamics and you always want a bit of back brakes before the front? In other words, should that valve be deleted/gutted if using discs in the rear? I am wondering if a kit like this has you gutting any stock valves, and just running straight tubing to the back, maybe with an adjustable proportioning valve on the rear line. Or, does it work with most of the stock stuff. Anybody got experience in this area? Thanks! Link to comment Share on other sites More sharing options...
85lebaront2 Posted April 8, 2022 Share Posted April 8, 2022 I did a rear disc conversion on my friend's 1995 F350 DRW truck which is a Sterling 10.25" full floating model. They do not have the residual pressure/proportioning valve as they have ABS. On Darth it was attached to the frame on a bracket directly under the master cylinder. I eliminated it when I went to the later booster and master cylinder. Link to comment Share on other sites More sharing options...
mat in tn Posted April 9, 2022 Share Posted April 9, 2022 I did a rear disc conversion on my friend's 1995 F350 DRW truck which is a Sterling 10.25" full floating model. They do not have the residual pressure/proportioning valve as they have ABS. On Darth it was attached to the frame on a bracket directly under the master cylinder. I eliminated it when I went to the later booster and master cylinder. I did the exact system you are asking about. ssbc rear disc conversion, aluminum master, rpv with pintle valve seat removed, adjustable proportioning valve. the system worked very well. however, for me it was not exactly a bolt on. the first part that I need to address is that not all axles are the same from one source to another. the manufacturing specs are as the original manufacturer required and that's where my first issue showed up. the axle flange on the new shafts were perfectly spec'd for the drums they are made for, yet the outer diameter was about 3/16 larger than the inside of the new rotor. so yes, I had them milled. the next issue is the rotors are obviously made for something with larger than 1/2-20 studs, so they come with filler rings to center on the studs. the next point was the bracket spacers that came with were not the correct thickness to center the caliper on the rotor so yes, I made them also. after that it was just the normal finicky job of making good brake lines that seal. buy a GOOD brake line flare tool and a good coiling tool. cheap equals leaks! Link to comment Share on other sites More sharing options...
Pete Whitstone Posted November 29, 2023 Author Share Posted November 29, 2023 I did the exact system you are asking about. ssbc rear disc conversion, aluminum master, rpv with pintle valve seat removed, adjustable proportioning valve. the system worked very well. however, for me it was not exactly a bolt on. the first part that I need to address is that not all axles are the same from one source to another. the manufacturing specs are as the original manufacturer required and that's where my first issue showed up. the axle flange on the new shafts were perfectly spec'd for the drums they are made for, yet the outer diameter was about 3/16 larger than the inside of the new rotor. so yes, I had them milled. the next issue is the rotors are obviously made for something with larger than 1/2-20 studs, so they come with filler rings to center on the studs. the next point was the bracket spacers that came with were not the correct thickness to center the caliper on the rotor so yes, I made them also. after that it was just the normal finicky job of making good brake lines that seal. buy a GOOD brake line flare tool and a good coiling tool. cheap equals leaks! I did the exact system you are asking about. ssbc rear disc conversion, aluminum master, rpv with pintle valve seat removed, adjustable proportioning valve. the system worked very well. however, for me it was not exactly a bolt on. the first part that I need to address is that not all axles are the same from one source to another. the manufacturing specs are as the original manufacturer required and that's where my first issue showed up. the axle flange on the new shafts were perfectly spec'd for the drums they are made for, yet the outer diameter was about 3/16 larger than the inside of the new rotor. so yes, I had them milled. the next issue is the rotors are obviously made for something with larger than 1/2-20 studs, so they come with filler rings to center on the studs. the next point was the bracket spacers that came with were not the correct thickness to center the caliper on the rotor so yes, I made them also. after that it was just the normal finicky job of making good brake lines that seal. buy a GOOD brake line flare tool and a good coiling tool. cheap equals leaks! Resurrecting this thread as I am moving along with this conversion. Still mostly in the planning and parts gathering stages. But for the rotors I am using, I am facing the same problem as you, the holes for the studs in the rotor are larger than the studs on the 9" axle. Did you buy the "filler rings" you refer to above, or fabricate them? The hole in the center of these rotors is too big for the nub on the 9" axle end. I was considering fabbing a ring to take up the distance, to make the brake rotor hub-centric. How to fix it in place I have not figured out yet. But filler rings on the studs is something I had not considered and might be the path of least resistance. My plan is to switch to the later (early 90s) plastic master cylinder, delete whatever proportioning valve is on it, install a manually adjustable proportioning valve near the MC, and delete or gut the stock residual pressure valve on the frame under the MC. Any gotcha's or need-to-knows with all that? Link to comment Share on other sites More sharing options...
Pete Whitstone Posted December 2, 2023 Author Share Posted December 2, 2023 I did the exact system you are asking about. ssbc rear disc conversion, aluminum master, rpv with pintle valve seat removed, adjustable proportioning valve. the system worked very well. however, for me it was not exactly a bolt on. the first part that I need to address is that not all axles are the same from one source to another. the manufacturing specs are as the original manufacturer required and that's where my first issue showed up. the axle flange on the new shafts were perfectly spec'd for the drums they are made for, yet the outer diameter was about 3/16 larger than the inside of the new rotor. so yes, I had them milled. the next issue is the rotors are obviously made for something with larger than 1/2-20 studs, so they come with filler rings to center on the studs. the next point was the bracket spacers that came with were not the correct thickness to center the caliper on the rotor so yes, I made them also. after that it was just the normal finicky job of making good brake lines that seal. buy a GOOD brake line flare tool and a good coiling tool. cheap equals leaks! Resurrecting this thread as I am moving along with this conversion. Still mostly in the planning and parts gathering stages. But for the rotors I am using, I am facing the same problem as you, the holes for the studs in the rotor are larger than the studs on the 9" axle. Did you buy the "filler rings" you refer to above, or fabricate them? The hole in the center of these rotors is too big for the nub on the 9" axle end. I was considering fabbing a ring to take up the distance, to make the brake rotor hub-centric. How to fix it in place I have not figured out yet. But filler rings on the studs is something I had not considered and might be the path of least resistance. My plan is to switch to the later (early 90s) plastic master cylinder, delete whatever proportioning valve is on it, install a manually adjustable proportioning valve near the MC, and delete or gut the stock residual pressure valve on the frame under the MC. Any gotcha's or need-to-knows with all that? Decided to forge my own trail rather than buy a kit. I'm just a glutton for punishment that way most times. I sourced an entire Dodge Ram 1500 rear axle of 2013 vintage off FB marketplace for cheap, then set about adapting the Dodge stuff to the 9 inch. It actually turned out to be not that difficult, but it did require some machining so I can't really recommend it as an easy solution. Specifically, the 4 Dodge mounting holes had to be welded up so the 9 inch pattern could be drilled partially on top of the Dodge holes. Then the center hole where the axle passes through had to be bored out about .400 larger. Then the caliper mounting brackets had to be sawed in half so they could be welded onto the other side of the 9 inch flange. Some photos to clarify. This will allow not only the conversion to discs, but also retain the parking brake function with some shoes that fit inside the rotor hat. Minor fiddly things yet to work out are how to interface the parking brake cables at the Ford end, how to make the Dodge rotors hubcentric, and so on, but that stuff should be pretty simple. The rotor dictates a larger wheel size than 15", that's one downside. But I have a set of 17" wheels (which, coincidentally are Dodge as well) that I run on the truck sometimes. That will have to become full time. More to come as the conversion progresses. Link to comment Share on other sites More sharing options...
Gary Lewis Posted December 2, 2023 Share Posted December 2, 2023 Decided to forge my own trail rather than buy a kit. I'm just a glutton for punishment that way most times. I sourced an entire Dodge Ram 1500 rear axle of 2013 vintage off FB marketplace for cheap, then set about adapting the Dodge stuff to the 9 inch. It actually turned out to be not that difficult, but it did require some machining so I can't really recommend it as an easy solution. Specifically, the 4 Dodge mounting holes had to be welded up so the 9 inch pattern could be drilled partially on top of the Dodge holes. Then the center hole where the axle passes through had to be bored out about .400 larger. Then the caliper mounting brackets had to be sawed in half so they could be welded onto the other side of the 9 inch flange. Some photos to clarify. This will allow not only the conversion to discs, but also retain the parking brake function with some shoes that fit inside the rotor hat. Minor fiddly things yet to work out are how to interface the parking brake cables at the Ford end, how to make the Dodge rotors hubcentric, and so on, but that stuff should be pretty simple. The rotor dictates a larger wheel size than 15", that's one downside. But I have a set of 17" wheels (which, coincidentally are Dodge as well) that I run on the truck sometimes. That will have to become full time. More to come as the conversion progresses. That's an interesting approach. Keep us apprised as someone else may want to follow in your steps. Link to comment Share on other sites More sharing options...
85lebaront2 Posted December 3, 2023 Share Posted December 3, 2023 That's an interesting approach. Keep us apprised as someone else may want to follow in your steps. On the bigger stuff, I believe the E-series 350 with dual rear wheels might be a good source. The kit my friend bought was from EGR brakes and it was real nightmare, nothing fit, it uses GM calipers with the discs being used for the E-brake and parking. I have lots of pictures and a write up I sent to EGR brakes. The bad things for me were (a) for a DRW truck, you need the E350 DRW rotors which are quite deep (b) these are designed to have a drum E-brake and parking brake inside the rotor (like my Lebaron has). Mine main objection to the combined hydraulic and mechanical caliper I just went through on my 2009 Flex, the seal around the parking brake screw started leaking on the left rear caliper, and it would sit there and drip without the brake being applied and would pretty well drain the R front/L rear circuit overnight. It is just a leak waiting to happen. Link to comment Share on other sites More sharing options...
Pete Whitstone Posted December 4, 2023 Author Share Posted December 4, 2023 Mine main objection to the combined hydraulic and mechanical caliper I just went through on my 2009 Flex, the seal around the parking brake screw started leaking on the left rear caliper, and it would sit there and drip without the brake being applied and would pretty well drain the R front/L rear circuit overnight. It is just a leak waiting to happen. I think the Dodge setup is different than what you are imagining. I don't know what part would be a "parking brake screw". The Dodge setup is just a levered wedge of sorts, completely divorced from the hydraulic system. I don't see how anything on it would have the capability to cause a leak on the hydraulic side. Link to comment Share on other sites More sharing options...
85lebaront2 Posted December 4, 2023 Share Posted December 4, 2023 Mine main objection to the combined hydraulic and mechanical caliper I just went through on my 2009 Flex, the seal around the parking brake screw started leaking on the left rear caliper, and it would sit there and drip without the brake being applied and would pretty well drain the R front/L rear circuit overnight. It is just a leak waiting to happen. I think the Dodge setup is different than what you are imagining. I don't know what part would be a "parking brake screw". The Dodge setup is just a levered wedge of sorts, completely divorced from the hydraulic system. I don't see how anything on it would have the capability to cause a leak on the hydraulic side. That would be my choice, Jaguar had a similar system, except the rotors, calipers and E-brake were all inboard right at the output shafts on the differential housing. Here is a shot of the caliper with the parking brake screw: Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted December 4, 2023 Share Posted December 4, 2023 Decided to forge my own trail rather than buy a kit. I'm just a glutton for punishment that way most times. I sourced an entire Dodge Ram 1500 rear axle of 2013 vintage off FB marketplace for cheap, then set about adapting the Dodge stuff to the 9 inch. It actually turned out to be not that difficult, but it did require some machining so I can't really recommend it as an easy solution. Specifically, the 4 Dodge mounting holes had to be welded up so the 9 inch pattern could be drilled partially on top of the Dodge holes. Then the center hole where the axle passes through had to be bored out about .400 larger. Then the caliper mounting brackets had to be sawed in half so they could be welded onto the other side of the 9 inch flange. Some photos to clarify. This will allow not only the conversion to discs, but also retain the parking brake function with some shoes that fit inside the rotor hat. Minor fiddly things yet to work out are how to interface the parking brake cables at the Ford end, how to make the Dodge rotors hubcentric, and so on, but that stuff should be pretty simple. The rotor dictates a larger wheel size than 15", that's one downside. But I have a set of 17" wheels (which, coincidentally are Dodge as well) that I run on the truck sometimes. That will have to become full time. More to come as the conversion progresses. Really interesting, Pete! Subscribed so i can follow along. Link to comment Share on other sites More sharing options...
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